Regenerative air-cooled gas turbine engine

ABSTRACT

A regenerative air-cooled gas turbine engine, particularly applicable to and adequately clean burning for automotive and like applications requiring small size at a power rating in the 100-400 h.p. range. The engine is characterized by having the compressor, combustor, drive and power turbines, and regenerator all concentric with the longitudinal axis. The cool air supplied from the compressor to the regenerator passes in a tubular shroud-like flow which surrounds all but the compressor end of the engine and thus encloses the hot section of the engine. Cool air direct from the compressor output is ducted to the combustor and pre-mixed with run fuel supplied by a slinger which separately introduces run fuel and start/idle fuel, the pressure of the latter being boosted by a damper bearing acting as a fuel pump. Simplicity and low manufacturing cost are achieved by having substantially all gas flow confining surfaces in the form of surfaces of revolution. Cooling of nozzle vanes and the drive turbine impeller blades by air ducted from the tubular flow allows turbine gas inlet temperatures of 2,200* F. and higher. The regenerator is of the rotary disc type and has low cost, easily maintained non-rubbing seals.

llnited States Patent 1 1 Beaufrere 1 June 25, 1974 REGENERATIVE AIR-COOLED GAS TURBINE ENGINE [76] Inventor: Albert H. Beaufrere, Private Rd.,

Huntington, NY. 11743 22 Filed: Oct.25, 1972 211 App1.No.:300,774

3,680,983 8/1972 Bell 60/3951 R 3,705,492 12/1972 Vickers 1 1 60/3951 H FOREIGN PATENTS OR APPLICATIONS 586.159 ll/l959 Canada 60/3951 H 548,809 11/1959 Canada 60/3951 H Primary Examiner-Carlton R. Croyle Assistant Examiner-Warren Olsen Attorney, Agent, or Firm-Roylance, Abrams, Berdo & Kaul [57 ABSTRACT A regenerative air-cooled gas turbine engine, particularly applicable to and adequately clean burning for automotive and like applications requiring small size at a power rating in the 100-400 h.p. range. The engine is characterized by having the compressor, combustor, drive and power turbines, and regenerator all concentric with the longitudinal axis. The cool air supplied from the compressor to the regenerator passes in a tubular shroud-like flow which surrounds all but the compressor end of the engine and thus encloses the hot section of the engine. Cool air direct from the compressor output is ducted to the combustor and pre-mixed with run fuel supplied by a slinger which separately introduces run fuel and start/idle fuel, the pressure of the latter being boosted by a damper bearing acting as a fuel pump. Simplicity and low manufacturing cost are achieved by having substantially all gas flow confining surfaces in the form of surfacesof revolution. Cooling of nozzle vanes and the drive turbine impeller blades by air ducted from the tubular flow allows turbine gas inlet-temperatures of 2,200 F. and higher. The regenerator is of the rotary disc type and has low cost, easily maintained non-rubbing seals.

20 Claims, 28 Drawing Figures PATENTEDJUNZSIHM saw 01 or 1a PAIENTEDJHNZBIW 3.818.696

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PATENTEDJUNZSIBH sum 11m 14 PATENTEU JUNZS I974 sum 12 or 14 PAIENTEBJUNZSIHH saw '13 ur 14 mi m9 m3 PAIENTEB JUN25I974 saw u OF M mmm REGENERATIVE AlR-COOLED GAS TURBINE ENGINE BACKGROUND OF THE INVENTION It has long been recognized that the inherent advantages of the turbine engine, particularly its inherent clean burning characteristics and its high power-tovolume ratio, make the turbine engine a desirable alternative to the reciprocating piston engine for many applications. However, the reciprocating piston engine having been more or less universally adopted, the automotive and other industries have very large investments in engine production facilities, and the design of automobiles and other products is predicated on the reciprocating piston engine, so that commercial interest in turbine engines has been inhibited. Recent antipollution requirements have increased the interest in all alternatives .to the reciprocating piston engine, and new advances in turbine engines have been made. To date, however, no turbine engine has been devised which is truly satisfactory for automotive and like applications.

Failure of prior-art workers to provide such an engine has resulted from a number of difiiculties. One problem is that overall engine efficiency, particularly part-load efficiency, is not being achieved at low cost if the turbine inlet gas temperature and matching pressure ratios are held low. Prior-art turbine engines suitable for automotive and like applications have allowed inlet gas temperatures of only, e.g., 1,700l88 F. at single stage compressor inlet-to-outlet pressure ratios of about 4: 1. Limitations on gas temperature have been applied by the temperature characteristics of the materials employed and the fact that engines intended for automotive applications have had no capability for cooling the turbine. As a result of acceptance of low inlet gas temperatures, acceptable efficiencies have been achieved only at the cost of using large, excessively expensive regenerators.

Regenerator characteristics themselves have posed additional difficulties, since prior-art regenerators have been unduly costly and difficult to seal and maintain when capable of providing heat exchange efficiencies acceptable for low cost automotive and similar applications. Finally, even assuming adequate engine efficiencies and an acceptable regenerator structure, prior-art workers have not been able to propose an overall engine configuration which would allow the engine to be small enough, and to be manufactured at a cost low enough, to satisfy the requirements posed by, e.g., the automotive industry.

OBJECTS OF THE INVENTION A general object of the invention is to devise a regenerative air-cooled gas turbine engine which meets the requirements of the automotive and like industries in terms of operating characteristics, size, weight and manufacturing cost.

Another object is to provide such an engine capable of operating at turbine gas inlet temperatures of 2,200 F. and more and which employs a high efficiency single-stage air compressor at pressure ratios of 6: 1-821.

A further object is to provide such an engine which, despite its improved operating characteristics, is

smaller, simpler and therefore lower in cost than the engines heretofore proposed.

Yet another object is to devise a turbine engine of the type described using a single disc type regenerator concentric with the longitudinal axis of the engine.

A still further object is to provide a small, low-cost turbine engine which is so clean burning as to meet the strictest anti-pollution standards.

Still another object is to devise such an engine in which the run fuel, as distinguished from. the start/idle fuel, is thoroughly premixed with cool primary air before or just as it enters the combustion zone.

A further object is to provide a low cost rotary disc regenerator with non-rubbing seals.

SUMMARY OF THE INVENTION Turbine engines according to the invention comprise a centrifugal compressor, an at least generally radial flow combustor, i.e., one of radial or mixed flow, an aircooled radial drive turbine, a free power turbine, and a rotary disc regenerator or heat exchanger, the compressor, combustor, turbines and heat exchanger all being coaxial, with the compressor located at one end of the engine and the heat exchanger at the other, and with the combustor surrounding the space between the compressor and its drive turbine. A generally tubular outer casing extends from the compressor to the heat exchanger and cooperates with a generally tubular wall spaced inwardly therefrom to define an outer tubular flow passage communicating between the compressor outlet and the air inlet of the heat exchanger, so that the relatively cool air from the compressor is directed in a shroud-like tubular flow which surrounds all of the hot section of the engine. Additional wall means, spaced inwardly from the tubular wall, cooperates therewith to define a combustor supply flow passage communicating between the air outlet of the heat exchanger and the air inlets of the combustor, and also cooperates with another inner wall means to define a tubular exhaust gas passage communicating between the power turbine outlet and the exhaust gas inlet of the heat exchanger. All of the gas flow passages are defined by surfaces of revolution or surfaces which are transverse, advantageously radial or helical, to the longitudinal axis of the engine. The combustor comprises an annular housing with generally radial side walls, defining the combustion chamber, and rotary fuel slinger means carried by the shaft which connects the drive turbine to the compressor, the arrangement being such that start- /idle fuel is handled separately from run fuel. All primary combustion air is relatively cool air supplied from the outer tubular flow passage or directly from the compressor, before the air is heated by the regenerator. The run fuel is pre-mixed with air before or just as it enters the combustion zone. Nozzle vanes for the turbines, and the impeller blades of the drive turbine, are all cooled by air ducted from the outer tubular flow passage. Coaxial with the drive turbine shaft, a separate power shaft carries the free power turbine rotor and extends through the center of the heat exchanger. The heat exchanger is of the rotary disc type, embodying non-rubbing matrix seals with air-cooled support r01 lers, and the heat exchanger bearing and power turbine bearings are carried by a common bearing support.

In order that the manner in which the foregoing and other objects are achieved according to the invention can be understood in detail, one particularly advantageous embodiment thereof will be disclosed with reference to the accompanying drawings, which fonn a part of the original disclosure hereof, and wherein:

FIG. 1 is a view, partially in longitudinal section and partially in side elevation, of a turbine engine according to one embodiment of the invention;

FIG. 2 is an end elevational view taken at the cold end of the engine of FIG. 1;

FIG. 3 is an end elevational view taken at the opposite end of the engine, with the gear box removed and parts broken away for clarity;

FIG. 4 is a fragmentary longitudinal sectional view of that portion of the engine of FIG. 1 extending from the right-hand (as viewed in FIG. 1) end of the engine through the compressor rotor;

FIG. 5 is a longitudinal sectional view of that portion of the engine extending from the compressor rotor through the power turbine;

FIG. 6 is a longitudinal sectional view of the remaining portion of the engine but with the gear box removed;

FIG. 7 is a view similar to FIG. 6 but taken on line 7-7, FIG. 3;

FIG. 8 is an enlarged fragmentary longitudinal sectional view illustrating the structure via which fuel is supplied to the engine;

FIG. 9 is a fragmentary transverse cross-sectional view taken generally on line 9-9, FIG. 5;

FIG. 10 is a fragmentary elevational view, with parts removed and broken away for clarity, showing a portion of the back shroud of the compressor;

FIGS. 11-15 are fragmentary sectional views taken generally on lines 11ll, 1212, 13-13, 1414, and l5-l5, respectively, FIG. 5;

FIG. 16 is a perspective view of the fuel slinger of the engine of FIG. 1;

FIG. 17 is an enlarged view, mainly in longitudinal section, of a portion of the structure shown in FIG. 5;

FIG. 18 is a fragmentary longitudinal sectional view taken at the location of one of the cooled nozzle vanes of the drive turbine of the engine;

FIG. 19 is an end elevational view, with parts broken away for clarity. of the nozzle vane of FIG. 18;

FIG. 20 is a sectional view taken generally on line 2020, FIG. 18;

FIG. 21 is a fragmentary end elevational view of the rotor of the drive turbine, with parts broken away for clarity;

FIG. 22 is a fragmentary longitudinal sectional view of the drive turbine rotor;

FIG. 23 is a transverse sectional view of one of the rotor blades of the drive turbine;

FIG. 24 is a perspective view of the leading edge portion of one of the drive turbine rotor blades, with parts broken away for clarity;

FIG. 25 is a transverse sectional view taken generally on line 2525, FIG. 6;

FIGS. 26 and 27 are fragmentary sectional views taken generally on lines 2626 and 27-27, FIG. 3, respectively; and

FIG. 28 is a fragmentary transverse sectional view of a portion of the heat exchanger matrix.

DETAILED DESCRIPTION 1. Overall Combination Referring to FIG. 1, the engine disclosed comprises a centrifugal compressor 1, an at least generally radial flow combustor 2, an air-cooled radial inflow drive turbine 3, a free power turbine 4, and a rotary heat exchanger 5, all of the components just recited being concentric with the longitudinal axis of the engine, compressor 1 being located at one end of the engine, heat exchanger 5 being located at the other end, and the combustor 2 surrounding the space between compressor l and drive turbine 3. The rotor 6 of turbine 3 is connected to rotor 7 of compressor 1 by a tubular shaft 8. The rotor 11 of power turbine 4 is secured to a shaft 12 which is coaxial with shaft 8 and projects through the center of heat exchanger 5. Shaft 12 is the output power shaft, being connected to the input of reduction gear box 13. Compressor l is a radial outflow centrifugal compressor operated at a pressure ratio of, e.g., 611-821, and the air discharged therefrom is conducted to heat exchanger 5 via a tubular flow passage 14 defined by tubular outer casing 15 and a tubular wall, indicated generally at 16, spaced inwardly from casing 15 and comprising members l7l9.

Outboard of heat exchanger 5 is a circular flat plate 20 having circumferentially spaced outwardly projecting cars 21 secured rigidly to like ears 22 on the end of wall member 16, as by screws 23. At the other side of the heat exchanger, a circular flat plate 24 has circumferentially spaced outwardly projecting ears 25 disposed between and rigidly secured to like cars 26 on wall member 17 and 18. Plate 20 has two diametrically spaced air inlet openings 27 and 28. Plate 24 has two diametrically spaced air outlet openings 29 and 30 axially aligned with openings 27, 28, respectively. In locations angularly spaced from the locations of air inlet openings 27 and 28, plate 20 has two diametrically spaced exhaust gas outlet openings 31 and 32. Similarly, plate 24 has two diametrically spaced exhaust gas inlet openings 33 and 34 axially aligned with openings 31 and 32, respectively.

A tubular wall, indicated generally at 35, and forming an integral part of a casting 9, is spaced inwardly from wall member 18 and cooperates therewith to define a tubular passage portion 36 communicating between air outlet openings 29, 30 of the heat exchanger, on the one hand, and the space within wall 19, on the other hand, the latter space being occupied by combustor 2.

Combustor 2 includes an outer wall member 37 and an inner wall member 38 which cooperate to define the combustion chamber and are of such shape as to define a circular gas discharge opening 39 which is disposed to discharge the combustion gases directly into the nozzle blade passage 40 of drive turbine 3, i.e., the space between an outer extension of back shroud member 41 of drive turbine 3 and an outer extension of outer shroud member 42 of the drive turbine. Drive turbine 3 is a radial inflow, cooled turbine which discharges into a flo'w passage 43 of S-shaped radial cross section defined by an annular member 44, which projects inwardly from wall member 35, and a member 45. The outer portion of passage 43 opens axially into the power turbine nozzle vane passage 46 defined by members 35 and 45.

Power turbine 4 is of the axial type and discharges into an annular flow diffusing passage 47, defined by members 35 and 35a and a cup-shaped inner wall sheel 48. Communicating with passage portion 36, the air outlet openings 29, are located outside of wall 35. Exhaust gas inlet openings 27 and 28 on the other hand, are located in the portion of plate 24 which extends inwardly of wall and therefore communicate with the generally tubular passage 47. Accordingly, the exhaust gases dischared by power turbine 4 are supplied to heat exchanger 5 via passage 47 and openings 27, 28. Passing through the heat exchanger as later described, the exhaust gases are conducted by tubes 49, 50 to the exhaust system 51 and thence to a point of discharge.

Heat exchanger 5 includes a rotary heat exchange disc, indicated generally at 52, driven byan electric motor 53. Heat exchange disc 52 is located between plates 20 and 24. A tubular support member 54 extends through central openings in plates 20, 24 and, as later described, is secured rigidly to plate 20. Power turbine shaft 12 extends freely through member 54, projecting axially therebeyond, and is supported on member 54 by anti-friction bearings 55 and 56. Heat exchange disc 52 is rotatably supported on member 54 by a carbon bearing 57.

2. Structure at Compressor End of the Engine At the compressor, or cold, end of the engine, the structure includes an end member 60, a'member 61 which serves both as a support member and an air inflow shroud member, and the outer shroud member 62 of compressor 1. Member includes a flat circular end wall 63, a short cylindrical outer wall 64, and an outwardly projecting transverse annular mounting flange 65. Member 61 is an integral casting and com prises a flat annular intermediate portion 66, a flat transverse annular outer portion 67 which is offset from portion 66 toward member 60 and has the same outer diameter as flange 65, a plurality of spacer portions 68 which extend from portion 67 in a direction which, in the completed structure, is longitudinal of the engine and toward the heat exchanger 5, and a hub portion indicated generally at 69. Hub portion 69 includes an annular portion 70 joined to the inner periphery of intermediate portion 66 and curving smoothly to terminate in a right cylindrical nose portion 71 which is concentric with the axis of shaft 8 and projects toward compressor l..Nose portion 7l is tubular and the bore therethrough opens 'into a larger diameter right cylindrical recess 72 at the opposite side of the hub portion 69. At its side opposite compressor 1, intermediate portion 66 is provided with two integrally formed tubular outwardly projecting bearing supports 73, one of which is seen at 73, FIG. 4 the two being angularly spaced by 45 about the axis of the engine.

Outer shroud member 62 of compressor 1 is an integral casting comprising a flat transverse annular portion 75, a cylindrical tubular inner portion 76 having an inner diameter substantially greater than the outer diameter of nose portion 72 of member 61 and which extends axially from portion toward member 61, a second flat transverse annular portion 77 whichextends outwardly from the end of portion 76, and an outer tubular portion 79 which extends from portion 75 toward heat exchanger 5. Portion 79 has a right cylindrical outer surface directly embraced'by the corresponding end portion 80 of outer casing 15.'Portion 75 projects outwardly beyond the outer surface of tubular portion 79 so that there is an exposed peripheral flange portion 78 of a diameter such that the corresponding ends of spacers 68 engage flange 78. A sleeve 8lembraces flange 78 and the adjacent part of tubular portion 79, the end of sleeve 81 being welded to the end of portion 80 of casing 15. Member 61 is secured rigidly to shroud member 62 by a plurality of screws 82 which extend through sleeve 81 and flange 78 and are each engaged in a threaded bore in the end of a different one of spacers 68.

Member 60 is similarly secured to member 61 by screws 83 each extending through flange 65 into a threaded bore in outer portion 67 of member 61.

Rotor 7 of compressor 1 embraces a tubular bolt shaft 85, later described, and is concentric with the longitudinal axis of the engine, defined by the bolt shaft. The rotor includes a hub 86 and blades 87 and occupies an axial position on bolt shaft such that the curved outer edges of blades 87 extend along lines closely adjacent to the adjacent inner surface of shroud member 62. Back shroud member 88 of compressor 1 comprises a generally flat' transverse annular portion 89, an inner hub 90 which also acts as a bearing support, and an outer tubular portion 91. Portion 75 of shroud member 62 and portion 89 of shroud member 88 are spaced apart axially of the engine and are mutually parallel, defining an outwardly directed radial flow channel leading to the space between concentric shroud portions 79 and 91. A plurality of channel diffusers 92 are engaged between shroud portions 75 and 89. The combination of shroud portions 75 and 89 and diffusers 92 is rigidly clamped by a plurality of axially extending bolts 93 which also serve to secure the inwardly projecting annular end portion 94 of wall member 19 and the outer peripheral portion 95 of a sheet metal air flow confining wall member 96, later described. Spaced concentrically inwardly from tubular portion 79 of shroud member 62, the outer tubular portion 91 of shroud member 88 carries a plurality of axial diffuser vanes 98 which are thus supported in the compressor discharge annulus defined by shroud portions 75 and 88. Thus, directionally controlled by vanes 98, the air from compressor 1 is discharged directly into the outer flow passage 14.

Portion 77 of shroud member 62 and portion 66 of member 61 are mutually parallel and spaced apart axially, a plurality of adjustable guide vanes 99 being disposed between portions 77 and 66 and secured, e.g., by dowel bolts 100. With the outer diameter of nose portion 72 of member 61 equal to the outer diameter of the adjacent end of hub 86 of compressor rotor 7, member 61 cooperates with portions 77 and 76 of shroud member 62 to define the inlet air flow channel for compressor 1. That channel opens outwardly directly into the space between portion 67 of member 61 and portion 75 of shroud member 62. Two annular support plates 101 are provided, each secured rigidly to and extending outwardly from a different one of flange 65 and shroud portion 78. A plurality of conventional swirl tube type dynamic air cleaner assemblies 102 are arranged between plates 101 in an annular series and are secured to plates 101, each air cleaner 102 being centered between a different pair of the spacers 68. Air cleaners 102 are so constructed and arranged as to pass air from the space surrounding the series of air cleaners inwardly into the space between portions 67 and 75 and, therefore, to the inlet air flow channel for compressor 1. Particulate matter removed from the air by cleaners 102 is delivered to a dust manifold (not shown) under reduced pressure induced, e.g., from engine exhaust gas flow.

An oil tank 105 of semi-annular configuration is secured to member 60. The two bearing supports 73 of member 61 are axially aligned respectively with complementary bearing supports 106 on wall 63 of member 60. Each support 73, 106 accommodates an antifriction bearing 108. The bearings accommodated by the two pairs of supports 73, 106, respectively support the shafts of a conventional electric starter motorgenerator 1 and an oil pump and fuel pump unit indicated generally at 107, FIGS. 2 and 4. The drive means for both the starter motor-generator and the pump unit being identical, only the drive for the pump unit, seen in FIG. 4, will be described. The hub of a gear 115 is journalled in the aligned bearings 108 and fixed to the drive shaft 112 of the pump unit. Gear 115, and the similar gear (not shown) for the motor-generator, are meshed with pinion 124, later described. Shaft 112 drives conventional oil pump 113, conventional fuel pump 114, and a conventional pneumatic-mechanical fuel control device 114a.

3. Shaft Assembly and Fuel Feed The combination of drive turbine rotor 6, tubular shaft 8, and compressor rotor 7 is secured together axially by bolt shaft 85. Shaft 8 is provided with splines 117, 118 at its respective ends, splines 117 being mated with face splines 119 on the adjacent end of rotor 6 and splines 118 being mated with face splines 120 on the adjacent end of rotor 7 so that the combination of rotors 6 and 7 and shaft 8 rotates as if integral. Compressor rotor 7 includes a tubular extension 121 of such length as to extend through and project beyond hub portion 69 of member 61. Supported in recess 72 of hub portion 69 are a roller bearing 122 and a seal 123 both of which engage the cylindrical outer surface of extension 122. Immediately beyond hub portion 69, the extension has secured thereto a pinion 124 which is meshed with gear 115.

Bolt shaft 85 extends for a short distance beyond the tip of extension 121 and the head 125 of the shaft is outwardly enlarged. Embracing bolt shaft 85 between pinion 124 and head 125 is the rotor 126 of a conventional permanent magnet type generator employed to generate a control signal dependent upon engine speed and also useful, if desired, as the primary generator. Rotor 126 coacts with a stator or field winding 127 carried partly by a cylindrical extension 128 which is integral with hub portion 69 of member 61 and partly by the wall of a central opening in wall 63 of member 60.

At its opposite end, bolt shaft 85 is threaded and carries a nut 129 engaged with the tip of a tubular extension 130 on drive turbine rotor 6. Accordingly, nut 129 cooperates with head 125 to apply an axial clamping force to the combination of members 6, 8 and 7.

On its outer side, wall 63 is provided with a short cylindrical hub, the inner end of which defines the central opening of the wall and an outer portion of which is of larger diameter to accommodate the outer flange 131 of a cup-shaped cover member 132 secured rigidly to member 60, as by screws 133. At its inner face, the end wall of member 132 has outer and inner cylindrical tubular projections 134 and 135, respectively, which are mutually concentric and concentric with the axis of bolt shaft 85. A start/idle fuel supply conduit 136 communicates with the annulus between projections 134,

and a run fuel supply conduit 137 communicates with the space within projection 135. An outer annular resilient metal bellows 138 has one of its ends secured in fluid-tight relation, as by brazing or gluing, to the tip of projection 134. An inner bellows 139 is similarly secured to the tip of projection 135. The remaining ends of bellows 138, 139 are secured to a carbon ring 140, FIG. 8, which bears in rubbing seal fashion against a hardened steel ring 141 fixed to the head of bolt shaft 85. The mating faces of rings 140 and 141 have opposed manifold grooves 142 and 143, respectively. Ring 140 has a plurality of through bores 144 opening into groove 142. Similarly, ring 141 has a plurality of through bores 145 opening into groove 143.

As shown in FIG. 9, bolt shaft 85 comprises a main tubular shaft member 146, which has a plurality of axially extending inner grooves 147, and a relatively thinwalled filler tube 148 which extends throughout the lengths of grooves 147 and covers the same. At head 125, the inner wall of shaft member 146 tapers sharply outwardly to embrace ring 141, and tube 148 projects through the central opening of ring 141 and is sealed in fluid-tight fashion thereto. There is thus an annular space 149, FIG. 8, into which both the bores 145 of ring 141 and the grooves 147 of member 146 open. Accordingly, start/idle fuel supplied by conduit 136 flows into the grooves 147, and run fuel supplied by conduit 137 flows into the interior of tube 148.

Supply of start/idle fuel via conduit 136 is controlled by an on-off valve (not shown) forming part of fuel control device 114a, the on-off valve being conventionally operated to supply start/idle fuel when the shaft assembly attains, e.g., about 15 percent of full rotational speed. Run fuel supplied via conduit 137 is controlled by conventional modulating and limiting control valves (not shown) in response to signals from generator 126, 127.

4. Combustor Shaft 8 is so located on bolt shaft 85 that, in the completed assembly, shaft 8 is axially centered with respect to the inner peripheral portions of combustor walls 37 and 38. Secured to the central portion of shaft 8, so as to rotate therewith, is a fuel slinger indicated generally at 155, FIGS. 16 and 17. Fuel slinger is an integral metal body having a central through bore which directly embraces shaft 8. The slinger body includes an inner hub portion 156 each face of which is equipped with a right cylindrical tubular axially projecting flange 157, a right cylindrical, tubular, axially projecting seal flange 158 concentric with the through bore and projecting axially therefrom in a location spaced a significant distance outwardly from flanges 157, and an outer peripheral disc portion 159 which is relatively thin as compared to the axial thickness of hub portion 156 and is of such diameter as to extend outwardly between the inner peripheral portions of combustor walls 37, 38. At its outer periphery, disc portion 159 has oppositely projecting tubular flanges 152 which are concentric with the shaft assembly. Since disc portion 159 is relatively thin and is axially centered on hub portion 156, hub portion 156 has right cylindrical outer peripheral surfaces 160 each on a different side of disc portion 158. A plurality of radial bores 161, FIGS. 8 and 17, extend completely through disc portion 159 and hub portion 156. Each bore 161 communicates with a different one of a like number of axial grooves 162 in the wall of the central through bore of the slinger body. Hub portion 156 is also provided with a plurality of pairs of outwardly diverging bores 163, each bore 163 of each pair opening outwardly through a different one of the outer surfaces 160 of the hub portion. At their inner ends, bores 163 of each pair join and register with one of a plurality of radial bores 164, FIG. 17, in shaft 8. Bores 164 open inwardly into an annular space 165 defined by a reduced diameter portion of bolt shaft member 146, that member in turn being provided with a plurality of radial bores 166 which are registered with like openings 167 in tube 148 and therefore communicate between the interior of tube 148 and space 165. As shown in FIG. 8, there are typically four bores 166 and eight bores 163, the bores 166 therefore being of larger diameter than are bores 164, and space 165 affording free communication between bores 166 and bores 163. Bores 166 are each located between a different adjacent pair of axial grooves 147. In a location to the left of the slinger (as viewed in FIG. a plug 168 closes the interior of tube 148 against fluid flow.

Hub and bearing support portion 90 of compressor shroud member 88 projects axially toward fuel slinger 155 and is concentric with and spaced outwardly from shaft 8. Portion 90 has an inner wall portion of larger diameter at 170 to accommodate a seal face ring and bearing retainer 171. The adjacent inner wall portion 172 is of smaller diameter to accommodate a bronze damper bearing 173 of plain cylindrical tubular form. The inner wall of portion 90 is completed by a portion 174 of still smaller diameter, that portion surrounding and being spaced only slightly outwardly from shaft 8. Wall portions 172 and 174 are joined by a transverse annular shoulder 175 which faces toward retaining ring 171. Each annular end face of bearing 173 is grooved to accommodate a high temperature silicone O-ring 176, one engaging ring 171 and the other engaging shoulder 175. Portion 90 has an inner annular recess 177 which is concentric with shaft 8 and opens toward the slinger to freely accommodate the corresponding tubular flange 157 of the slinger. Outwardly of recess 177, portion 90 is completed by a tubular element 90a, secured by threads at its end opposite the slinger. Portions 90 and 90a cooperate to define an annular recess 178, coaxial with shaft 8 and opening 7 toward the slinger, to freely accommodate the corresponding seal flange 158 of the slinger. The inner and outer walls of recess 178 are right cylindrical and spaced slightly from the inner and outer surfaces, respectively, of flange 158. Outwardlyof recess 178, portion 90 has an annular end face which is provided with a circular groove 179 concentric with shaft 8 and opening toward the corresponding face of slinger portion 156.

Back shroud 41 of compressor drive turbine 3 comprises a hub and bearing support portion 180 which is complementary to portion 90 of compressor shroud 88. Thus, shroud portion 180 includes larger diameter inner wall portion 181, to accommodate seal face ring and bearing retainer 182, an adjacent inner wall portion 183 of smaller diameter, to accommodate a bronze damper bearing 184, and an inner wall portion 185, of still smaller diameter, spacedslightly outwardly from shaft 8. Wall portions 183 and 185 are joined by a transverse annular shoulder 186. Bearing 184 is disposed between retainer 182 and shoulder 186, the end faces of the bearing being suitably grooved to accommodate high temperature silicone O-rings 187. Portion 180 has an inner annular access 188 which iscomplementary to recess 177 and accommodates the corresponding tubular flange 157. Outwardly of recess 188, portion 180 is completed by a tubular element 180a secured by threads at its end opposite the slinger. Portions 180 and 180a cooperate to define an annular recess 189 which is complementary to recess 178 and accommodates the corresponding seal flange 158.

The axial position of hub and bearing support portion of compressor shroud member 88 is fixed by the annular series of bolts 93. Similarly, with transverse annular portion 191 to drive turbine shroud member 41 secured rigidly by an annular series of bolts 192 to shroud member 42, and that member being secured to the integral casting 9, which includes wall 18 and is later described, the axial position of hub and bearing support portion of shroud member 41 is fixed. The fuel slinger hub is fixed on shaft 8 and the axial position of shaft 8 in the overall assembly is fixed. Accordingly, the slinger is centered between shroud portions 90 and 180, sith only small clearances between the opposing transverse surfaces of the fuel slinger, on the one hand, and shroud portions 90 and 180, on the other hand.

At each side of the fuel slinger hub, shaft 8 has elongated portions embraced respectively by the bearings 173 and 184. The outer surfaces of these portions of shaft 8 are provided with helical pumping grooves 196 and 197, respectively, FIG. 17. Groove 196 opens into a transverse annular groove 198, at the end remote from slinger 155, and into a transverse annular groove 199 atslinger 155, groove 199 commmunicating directly with all of the axial grooves 162 in the slinger hub. Groove 197 similarly opens into transverse annular grooves 200 and 201, the latter groove also communicating with all of the grooves 162. Shaft 8 and bolt shaft member 146 are provided with a plurality of sets of aligned radial bores 202, 203, respectively, each set communicating between a different one of bolt shaft grooves 147 and groove 198. At the other end of shaft 8, that shaft and shaft member 146 are provided with a plurality of sets of radial bores 204, 205, respectively, each such set communicating between a different one of grooves 147 and groove 200. Accordingly, whenever start/idle fuel is supplied via conduit 136, FIG. 8, that fuel is supplied to both grooves 198 and 200. The combination of bearing 173 and ring 171 embraces the portion of shaft 8 which includes grooves 196, 198 and 199 and efiectively covers those grooves. Similarly, the combination of bearing 184 and ring 182 embraces the portion of shaft'8 which includes grooves 197, 200 and 201 and effectively covers those grooves. The helical grooves 196 and 197 are oriented to move the fuel from grooves 198 and 200 inwardly to grooves 199 and 201, as the shaft assembly rotates during operation of the engine, and the fuel so moved is supplied via grooves 162 to the radial bores 161 of slinger 155. R0- tation of the slinger causes the fuel to be projected outwardly into the combustion chamber as later described. Simultaneously, any fuel supplied to slinger bores 163 is also projected outwardly.

At the end of shaft 8 adjacent drive turbine 3, a labyrinth gas seal 206 embraces shaft 8 and has its fins positioned to cooperate with ring 182. Shroud portion 180 has a shallow annular recess which accommodates a radially elongated web 207 which forms an integral part of seal 206 and has a peripheral lip 208 which engages the outer peripheral portion of drive turbine bine rotor 6, for a purpose later described. Just outwardly of wall 

1. In a regenerative air-cooled gas turbine engine, the combination of a centrifugal compressor; a radial turbine; combustor means comprising wall means defining an annular, at least generally radial flow combustion chamber, fuel supply means, and secondary air inlet means; a rotary disc regenerator having air inlet means and exhaust gas outlet means at one face of the disc and air outlet means and exhaust gas inlet means at the other face of the disc; support means operatively supporting said compressor, said turbine and said regenerator, said compressor being located at one end of the engine and said disc regenerator being located at the other end of the engine, said combustor means being located between said compressor and said turbine, said one face of the disc of said regenerator being directed away from said compressor; means defining a generally tubular outer flow passage communicating between the outlet of said compressor and the air inlet means of said regenerator, said generally tubular outer flow passage surrounding said regenerator and the components of said engine located between said regenerator and said compressor; means defining a generally tubular intermediate flow passage communicating between the air outlet means of said regenerator and the secondary air inlet means of said combustor means, said intermediate flow passage being surrounded by said outer flow passage; and means defining an inner flow passage surrounded by said intermediate flow passage and communicating between the outlet of said turbine and the exhaust gas inlet means of said regenerator.
 2. The combination defined in claim 1, wherein said fuel supply means comprises means defining at least one mixing chamber communicating with said combustion chamber, and means for supplying fuel to said mixing chamber; the combination further comprising duct means communicating between said outer flow passage and said mixing chamber for supplying relatively cool air to said mixing chamber.
 3. The combination defined in claim 2, wherein said combustor means comprises primary air inlet means for said combustion chamber, and said duct means communicates with both said mixing chamber and said primary inlet means.
 4. The combination defined in claim 1, wherein said support means comprises a first shaft means interconnecting said compressor and said turbine, said turbine driving said compressor via said first shaft means; and said fuel supply means comprises rotary slinger means carried by said first shaft means, and means defining at least one annular preliminary mixing chamber communicating with said combustion chamber, said slinger means being constructed and arranged to project fuel into said preliminary mixing chamber in one swirl direction; the combination further comprising means defining an annular series of directional ducts arranged to discharge air into said preliminary mixing chamber in opposition to said one swirl direction; and duct means communicating between said outer flow passage and said directional ducts.
 5. The combination defined in claim 4, wherein said combustor means further comprises a plurality of swirl vanes arranged in an annular series surrounding said annular preliminary mixing zone, said swirl vanEs being disposed in the path of the fuel-air mixture discharged from said preliminary mixing zone and being so shaped and arranged as to oppose the swirl direction imparted to the fuel by rotation of said slinger.
 6. The combination defined in claim 5, wherein said combustor means comrises a plurality of directional primary air inlets arranged in an annular series surrounding said swirl vanes, said directional primary air inlets being oriented to direct air in the same swirl direction as that imparted to the fuel-air mixture by said swirl vanes; said duct means communicating with both said directional ducts and said directional primary air inlets.
 7. The combination defined in claim 1, wherein said support means comprises a first shaft means carrying the rotors of said compressor and said turbine, said turbine driving said compressor via said first shaft means; said wall means comprises two annular wall portions which surround said first shaft means and are spaced apart axially thereof; and said fuel supply means comprises rotary slinger means carried by said first shaft means and located between said annular wall portions, means defining two annular preliminary mixing chambers communicating with said combustion chamber and each disposed adjacent a different one of said wall portions, said slinger means being constructed and arranged to project fuel into both of said preliminary mixing chambers in the same swirl direction; the combination further comprising means defining two annular series of air directing means, each of said series of air directing means being disposed to direct air into a different one of said preliminary mixing chambers in opposition to the swirl direction of the fuel projected by said slinger means; means defining a first set of flow passages communicating between said outer flow passage, in a first location at the outlet of said compressor, and one of said series of air directing means; and means defining a second set of flow passages communicating between said outer flow passage, in a second location downstream from said compressor, and the other of said series of air directing means.
 8. The combination defined in claim 7, wherein said turbine comprises a plurality of nozzle vanes each having an internal through passage and cooling passages, and said second set of flow passages includes means for conducting air from said outer flow passage to both said through passages of said nozzle vanes and said cooling passages of said nozzle vanes, and other means communicating between said through passages of said nozzle vanes and said other series of air directing means.
 9. The combination defined in claim 7, wherein said compressor includes a shroud member having an annular face directed toward said combustor means, said first set of flow passages including grooves in said face of said compressor shroud member; and said turbine includes a shroud member having an annular face directed toward said combustor means, said second set of flow passages including grooves in said face of said turbine shroud member.
 10. The combination defined in claim 1, wherein said turbine comprises a rotor including a hub having a larger end face and an exducer end face, and a plurality of blades carried by said hub and each having radial cooling passages; the combination further comprising flow passage means communicating with said outer flow passage and arranged to direct air from said outer flow passage over at least said larger end face of said hub and through said radial cooling passages.
 11. The combination defined in claim 1, wherein said turbine comprises a rotor including a hub, and a plurality of blades carried by said hub and each comprising a sheet metal member defining cooling passages extending radially through the blade; the combination further comprising passage means communicating witH said outer flow passage and arranged to direct air therefrom through said cooling passages of said blade.
 12. The combination defined in claim 1 and further comprising a tubular support member; means mounting said support member coaxially with respect to said turbine, said regenerator having a central hub through which said support member extends; bearing means rotatably supporting said regenerator on said support member; and cooling passage means communicating with said outer flow passage and arranged to direct air from said outer flow passage in cooling flow relative to said bearing means.
 13. The combination defined in claim 1, wherein said means defining said outer flow passage, said means defining said intermediate flow passage, and said means defining said inner flow passage all have passage-defining surfaces which are concentric with the longitudinal axis of the engine.
 14. The combination defined in claim 1, wherein said support means includes a shaft interconnecting the rotors of said turbine and said compressor whereby said compressor is driven by said turbine; said wall means of said combustor means includes a first wall member having an outer tubular portion concentric with said shaft and projecting toward said turbine, and an inner transverse annular portion, and a second wall member having an outer tubular portion concentric with said shaft and of smaller diameter than the outer tubular portion of said first wall member and an inner transverse annular portion, said outer tubular portion of said second wall member being spaced inwardly from said outer tubular portion of said first wall member, said two outer tubular portions defining an annular outlet for the combustor, said transverse annular portions extending inwardly toward said shaft in locations between said turbine and said compressor; said fuel supply means comprises a rotary slinger carried by said shaft in a position between said transverse annular portions of said first and second wall members; said means defining said outer flow passage comprising an outer annular wall member, and a second annular wall member spaced inwardly from said outer wall member; said means defining said intermediate flow passage comprising said second annular wall member and said first wall member of said combustor.
 15. In a regenerative air-cooled gas turbine engine, the combination of a centrifugal compressor; a radial turbine; a shaft interconnecting the rotors of said turbine and compressor, whereby said compressor is driven by said turbine; combustor means comprising wall means defining an annular, at least generally radial flow combustion chamber having an annular entrance portion surrounding said shaft in a location between said compressor and said turbine, a rotary slinger carried by said shaft and operatively disposed relative to said entrance portion of said combustion chamber, means defining an annular preliminary mixing chamber surrounding said slinger and constructed and arranged to receive fuel therefrom, an annular series of directional primary air inlets surrounding said preliminary mixing chamber and arranged to direct air into said combustion chamber with a predetermined swirl direction, and secondary air inlet means; a rotary regenerator having air inlet means, air outlet means, exhaust inlet means, and exhaust outlet means; first flow passage means communicating between the outlet of said compressor and the air inlet means of said regenerator; second flow passage means communicating between the air outlet means of said regenerator and said secondary air inlet means of said combustor means; third passage means communicating between the outlet of said turbine and the exhaust inlet means of said regenerator; and fourth passage means communicating between said first flow passage means and both said preliminary mixing chamber and said dirEctional primary air inlets.
 16. The combination defined in claim 14 and further comprising means defining a first set of flow passages communicating between said tubular outer flow passage at the outlet of said compressor and a fuel-air mixing area adjacent said slinger, said first set of flow passages including portions spaced axially from said transverse annular portion of said first combustor wall member toward said compressor; and means defining a second set of flow passages communicating between said tubular outer flow passage, in a location downstream from the outlet of the compressor, and a fuel-air mixing area adjacent said slinger, said second set of flow passages including portions spaced axially from said transverse annular portion of said second combustor wall member toward said turbine.
 17. The combination defined in claim 16, wherein said compressor comprises a shroud member having an annular face directed toward said combustor means; said means defining said first set of flow passages includes grooves in said face of said compressor shroud member; said turbine includes a shroud member having an annular face directed toward said combustor means; and said means defining said second set of flow passages includes grooves in said face of said turbine shroud member.
 18. The combination defined in claim 17, wherein said means defining said first set of flow passages comprises an annular wall member overlying said face of said compressor shroud member and having at its inner peripheral portion an outwardly projecting flange secured to an inner peripheral portion of said first combustor wall member; and said means defining said second set of flow passages comprises an annular wall member overlying said face of said turbine shroud member and having at its inner peripheral portion an outwardly projecting flange secured to an inner peripheral portion of said second combustor wall member.
 19. The combination defined in claim 17, wherein said turbine comprises a second shroud member, said second shroud member having an outer annular portion secured to said outer annular portion of said first combustor wall member, said first-mentioned turbine shroud member having an outer annular portion secured to said outer annular portion of said second combustor wall member, said turbine shroud members cooperating to define an annular nozzle vane passage which receives the combustion gases discharged from said combustor means, and a plurality of nozzle vanes mounted in said nozzle vane passage and each having cooling passages and a transverse through passage; and said means defining said second set of flow passages comprises said nozzle vanes, said through passages of said nozzle vanes being in communication with said grooves of said first mentioned turbine shroud member, and additional passage means communicating between said tubular outer flow passage and said through passage of said nozzle vanes.
 20. The combination defined in claim 19, wherein said turbine includes a rotor comprising a hub having an end of larger diameter, and a plurality of blades carried by said hub and each having radial flow channels; the combination further comprising rotor cooling passage means communicating with said additional passage means and arranged to direct cooling air across the larger diameter end of said rotor and outwardly through said radial flow channels of said blades. 